The present invention relates to an apparatus for the transfer of a very small defined quantity of a sample or specimen from an outer space to a reagent contained in a measuring or test chamber via a transfer slide mechanism that is displaceably disposed in a housing bore embodied as a valve or sealing seat and that is provided with passage or channel means that forms or establishes the specimen quantity and is embodied as a capillary tube, whereby the channel means is adapted to be moved out of a filling position, where it is disposed in front of a receiving opening that communicates with the outer space in order to fill the channel means with the specimen quantity, and into a measuring or test position in such a way that at the same time the receiving opening is closed by the transfer slide mechanism and the specimen quantity is introduced into the test chamber in order to empty the channel means.
DE-OS 3 507 032 discloses a transfer apparatus of this general type that is embodied as a disposable device and is essentially made of plastic; with this known device, a very small defined quantity of a specimen can be introduced into a hermetically sealed test chamber that contains a reagent without thereby having to negate the sealed aspect of the test chamber. Unfortunately, with this known apparatus, due to adhesion and/or capillary forces, some of the specimen can penetrate the sealing seat between the transfer slide mechanism and the housing bore during filling of the channel means in the slide mechanism that forms or establishes the specimen quantity. These microdrops of specimen that adhere to the transfer slide mechanism thus, in addition to the defined quantity of specimen, also enter the test chamber and therefore alter the specimen size that is to be delivered to the test chamber; this, for example by quantitative analysis, leads to significant incorrect or erroneous measurements.
It is therefore an object of the present invention to provide an apparatus for the transfer of a very small defined quantity of a specimen from an outer space into a test chamber where manufacturing tolerances and in particular physical parameters such as adhesion and capillary forces do not alter the magnitude of the defined specimen quantity that is to be delivered to the test chamber.